In the past, paging devices were restricted to short voice and data messages due to communication system bandwidth restrictions and paging device technology limitations. Technology improvements in circuit integration and digital voice and data compression algorithms have expanded the capability of messaging systems. Digital voice compression algorithms limit the amount of information transmitted to a receiving device, thus, providing a more efficient use of the communication system bandwidth. Although bandwidth utilization has been improved by digital voice compression algorithms, these algorithms have raised the performance and circuit requirements of the processing units used by the receiving devices.
Today's paging protocols use sophisticated error correction codes to improve the reliability of data message transmissions. With error correcting codes, a corrupt message can be reconstructed as long as the bit errors do not surpass the capabilities of the error correcting code. For one-way communication systems, where re-transmission requests of corrupt messages is not possible, error correcting codes provide a necessary mechanism for improving the reliability of message delivery.
Digital voice and data compression algorithms include in many instances the use of error correcting codes in the compressed message. In cases such as these, sending a compressed digital voice message which already includes a first level of error correction in a protocol which adds the overhead of a second level of error correction results in an inefficient use of the communication bandwidth.
Thus, what is needed is a method and apparatus for selectively encoding voice and data messages transmitted to receiving devices.